U.S. patent number 5,676,696 [Application Number 08/642,343] was granted by the patent office on 1997-10-14 for modular bifurcated intraluminal grafts and methods for delivering and assembling same.
This patent grant is currently assigned to InterVascular, Inc.. Invention is credited to Jean Paul Marcade.
United States Patent |
5,676,696 |
Marcade |
October 14, 1997 |
**Please see images for:
( Certificate of Correction ) ** |
Modular bifurcated intraluminal grafts and methods for delivering
and assembling same
Abstract
A bifurcated graft is formed from a series of individual
components which are intraluminally delivered apart from one
another and then assembled to form a fully supported structure. The
modular system includes a base member and one or more grafts
connected thereto. The base member preferably includes a portion
which gradually increases in diameter. A tubular device for
inserting the components of the modular system and a method
employing the modular system for repairing an abdominal aortic
aneurysm are also disclosed.
Inventors: |
Marcade; Jean Paul (La
Rochelle, FR) |
Assignee: |
InterVascular, Inc.
(Clearwater, FL)
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Family
ID: |
23555880 |
Appl.
No.: |
08/642,343 |
Filed: |
May 3, 1996 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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393701 |
Feb 24, 1995 |
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Current U.S.
Class: |
623/1.35;
606/191 |
Current CPC
Class: |
A61F
2/07 (20130101); A61F 2/95 (20130101); A61F
2/90 (20130101); A61F 2230/0067 (20130101); A61F
2230/008 (20130101); A61F 2/954 (20130101); A61F
2002/065 (20130101); A61F 2230/0078 (20130101); A61F
2250/0037 (20130101); A61F 2220/0033 (20130101); A61F
2/89 (20130101); A61F 2220/0075 (20130101); A61F
2250/0039 (20130101); A61F 2002/075 (20130101) |
Current International
Class: |
A61F
2/06 (20060101); A61F 002/06 (); A61M 029/00 () |
Field of
Search: |
;623/1,12
;606/198,191,153,108,194,195 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2065634 |
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Oct 1992 |
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CA |
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0539237A1 |
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Apr 1993 |
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EP |
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9319267 |
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Apr 1994 |
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DE |
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22477696A |
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Mar 1992 |
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GB |
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WO82/01647 |
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May 1982 |
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WO |
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WO92/01425 |
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Feb 1992 |
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WO |
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WO95/16406 |
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Jun 1995 |
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WO |
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Other References
Chuter, T., "Bifurcated Endovaccular Graft Insertion for Abdominal
Aortic Aneurysm," from Greenhalgh, Vascular and Endovascular
Surgical Techniques, 3rd Edition, 1994, pp. 92-99. .
Parodi, J.C., "Transfemoral Intraluminal Graft Implantation for
Abdominal Aortic Aneurysms," from Greenhalgh, Vascular and
Endovascular Surgical Techniques, 3rd Edition, 1994, pp. 71-77.
.
Moore, W.S., "Transfemoral Endovascular Repair of Abdominal Aortic
Aneurysm Using the Endovascular Graft System Device," from
Greenhalgh, Vascular and Endovascular Surgical Techniques, 3rd
Edition, 1994, pp. 78-91. .
Criado et al., "Transluminal Recanalization, Angioplasty and
Stenting in Endovascular Surgery: Techniques and Applications,"
from Greenhalgh, Vascular and Endovascular Surgical Techniques, 3rd
Edition, 1994, pp. 49-70. .
Marin et al., "Endoluminal Stented Graft Aorto-Bifemoral
Reconstruction," from Greenhalgh, Vascular and Endovascular
Surgical Techniques, 3rd Edition, 1994, pp. 100-104. .
May et al., "Transluminal Placement of a Prosthetic Graft-Stent
Device for Treatment of Subclavian Artery Aneurysm," Journal of
Vascular Surgery, vol. 18, No. 6, Dec. 1993, pp. 1056-1059. .
Chuter et al., "Transfemoral Endovascular Aortic Graft Placement,"
Journal of Vascular Surgery, vol. 18, No. 2, Aug. 1993, pp.
185-197. .
Parodi et al., "Transfemoral Intraluminal Graft Implantation for
Abdominal Aortic Aneurysms," Annals of Vascular Surgery, vol. 5,
No. 6, 1991, pp. 491-499..
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Primary Examiner: Willse; David H.
Attorney, Agent or Firm: Lerner, David, Littenberg, Krumholz
& Mentlik
Parent Case Text
This is a division of application Ser. No. 08/393,701 filed Feb.
24, 1995.
Claims
We claim:
1. A method for repairing a tubular anatomical structure having a
proximal branch and a pair of distal branches projecting from said
proximal branch at a point of bifurcation, said method comprising
the steps of:
providing a first tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end,
providing a base member foldable radially between a collapsed
configuration and an expanded configuration and having an inlet and
first and second outlets,
providing a primary tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end,
feeding said first limb in said collapsed configuration through one
of said distal branches until said proximal end of said first limb
is positioned adjacent said point of bifurcation, and said distal
end of said first limb is positioned within said one of said distal
branches,
expanding said first limb from said collapsed configuration to said
expanded configuration whereupon said first limb engages and
becomes secured within said one of said distal branches,
feeding said base member in said collapsed configuration through
said one of said distal branches and said first limb until said
inlet is positioned in said proximal branch, said first outlet is
positioned within said proximal end of said first limb, and said
second outlet is at least partially aligned with another one of
said distal branches,
expanding said base member from said collapsed configuration to
said expanded configuration, whereupon said first outlet engages
said proximal end of said first limb in friction fit
circumferential contact to join said first outlet of said base
member to said first limb,
feeding said primary limb in said collapsed configuration through
one of said distal branches and one of said first and second
outlets of said base member until said proximal end of said primary
limb is positioned in said proximal branch and said distal end of
said primary limb is positioned within said inlet of said base
member, and
expanding said primary limb from said collapsed configuration to
said expanded configuration, whereupon said distal end of said
primary limb engages said inlet in friction fit circumferential
contact to join said primary limb to said inlet of said base member
and said proximal end of said primary limb engages and becomes
secured within said proximal branch.
2. The method as claimed in claim 1, further comprising the steps
of:
providing a second tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end,
feeding said second limb in said collapsed configuration through
said another one of said distal branches until said proximal end of
said second limb is positioned within said second outlet of said
base member and said distal end of said second limb is positioned
within said another one of said distal branches, and
expanding said second limb from said collapsed configuration to
said expanded configuration, whereupon said proximal end of said
second limb engages said second outlet of said base member in
friction fit circumferential contact to join said second limb to
said second outlet of said base member and said distal end of said
second limb engages and becomes secured within said another one of
said distal branches.
3. The method as claimed in claim 2, wherein said steps of feeding
and expanding said second limb occur prior to said steps of feeding
and expanding said primary limb.
4. A method for repairing a tubular anatomical structure having a
proximal branch and a pair of distal branches projecting from said
proximal branch at a point of bifurcation, said method comprising
the steps of:
providing a base member foldable radially between a collapsed
configuration and an expanded configuration and having an inlet and
first and second outlets,
providing a primary tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end,
feeding said base member in said collapsed configuration through
one of said distal branches until said inlet is positioned in said
proximal branch, said first outlet is positioned within said one of
said distal branches, and said second outlet is at least partially
aligned with another one of said distal branches,
expanding said base member from said collapsed configuration to
said expanded configuration, whereupon said first outlet engages
and becomes secured within said one of said distal branches,
feeding said primary limb in said collapsed configuration through
one of said distal branches and one of said first and second
outlets of said base member until said proximal end of said primary
limb is positioned in said proximal branch and said distal end of
said primary limb is positioned within said inlet of said base
member, and
expanding said primary limb from said collapsed configuration to
said expanded configuration, whereupon said distal end of said
primary limb engages said inlet in friction fit circumferential
contact to join said primary limb to said base member and said
proximal end of said primary limb engages and becomes secured
within said proximal branch.
5. The method as claimed in claim 4, further comprising the steps
of:
providing a first tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end,
feeding said first limb in said collapsed configuration through
said another one of said distal branches until said proximal end of
said first limb is positioned within said second outlet of said
base member and said distal end of said first limb is positioned
within said another one of said distal branches, and
expanding said first limb from said collapsed configuration to said
expanded configuration, whereupon said proximal end of said first
limb engages said second outlet of said base member in friction fit
circumferential contact to join said first limb to said second
outlet of said base member and said distal end of said first limb
engages and becomes secured within said another one of said distal
branches.
6. A method for repairing a tubular anatomical structure having a
proximal branch and a pair of distal branches projecting from said
proximal branch at a point of bifurcation, said method comprising
the steps of:
providing a primary tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end;
providing a base member foldable radially between a collapsed
configuration and an expanded configuration and having a proximal
end and a distal end;
feeding said primary limb in said collapsed configuration through
one of said distal branches until said primary limb is positioned
entirely in said proximal branch;
expanding said primary limb from said collapsed configuration to
said expanded configuration, whereupon said primary limb engages
and becomes secured within said proximal branch;
feeding said base member in said collapsed configuration through
one of said distal branches until said proximal end of said base
member is positioned within said distal end of primary limb and
said distal end of said base member rests upon said point of
bifurcation; and
expanding said base member from said collapsed configuration to
said expanded configuration, whereupon said proximal end of said
base member engages said distal end of said primary limb in
friction fit circumferential contact to join said base member to
said primary limb.
7. A method for repairing a tubular anatomical structure having a
proximal branch and a pair of distal branches projecting from said
proximal branch at a point of bifurcation, said method comprising
the steps of:
providing a primary tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end;
providing a base member foldable radially between a collapsed
configuration and an expanded configuration and having a proximal
end, a distal end and first and second passageways providing
communication between said proximal and distal ends;
providing a first tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end;
feeding said primary limb in said collapsed configuration through
one of said distal branches until said primary limb is positioned
entirely in said proximal branch;
expanding said primary limb from said collapsed configuration to
said expanded configuration, whereupon said primary limb engages
and becomes secured within said proximal branch;
feeding said base member in said collapsed configuration through
one of said distal branches until said proximal end of said base
member is positioned within said distal end of said primary
limb;
expanding said base member from said collapsed configuration to
said expanded configuration, whereupon said proximal end of said
base member engages said distal end of said primary limb in
friction fit circumferential contact to join said base member to
said primary limb;
feeding said first limb in said collapsed configuration through one
of said distal branches until said proximal end of said first limb
is positioned within one of said first and second passageways of
said base member and said distal end of said first limb is
positioned within said one distal branch; and
expanding said first limb from said collapsed configuration to said
expanded configuration, whereupon said proximal end of said first
limb engages said one of said first and second passageways of said
base member in friction fit circumferential contact to join said
first limb to said base member and said distal end of said first
limb engages and becomes secured within said one distal branch.
8. The method as claimed in claim 7, further comprising the steps
of:
providing a second tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end,
feeding said second limb in said collapsed configuration through
another one of said distal branches until said proximal end of said
second limb is positioned within another one of said first and
second passageways of said base member and said distal end of said
second limb is positioned within said another one of said distal
branches, and
expanding said second limb from said collapsed configuration to
said expanded configuration, whereupon said proximal end of said
second limb engages said another one of said first and second
passageways of said base member in friction fit circumferential
contact to join said second limb to said base member and said
distal end of said second limb engages and becomes secured within
said another one of said distal branches.
Description
FIELD OF THE INVENTION
The present invention relates to bifurcated intraluminal grafts,
particularly for repairing defects in arteries and other lumens
within the body. More particularly, the present invention relates
to modular systems for forming bifurcated grafts and to methods for
delivering and assembling same in situ for repairing defective body
lumens, and particularly abdominal aortic aneurysms.
BACKGROUND OF THE INVENTION
An abdominal aortic aneurysm is a sac caused by an abnormal
dilation of the wall of the aorta as it passes through the abdomen.
The aorta is the main artery of the body, supplying blood to all
organs and parts of the body except the lungs. It arises from the
left ventricle of the heart, passes upward, bends over and passes
down through the thorax and through the abdomen, and finally
divides into the two iliac arteries which supply blood to the
pelvis and lower extremities.
The aneurysm ordinarily occurs in the portion of the aorta below
the kidneys. When left untreated, the aneurysm will eventually
cause the sac to rupture with ensuing fatal hemorrhaging in a very
short time. The repair of abdominal aortic aneurysms has typically
required major abdominal surgery in which the diseased and
aneurysmal segment of the aorta is removed and replaced with a
prosthetic device, such as a synthetic graft.
As with all major surgeries, there are many disadvantages to the
foregoing surgical technique, the foremost of which is the high
mortality and morbidity rate associated with surgical intervention
of this magnitude. Other disadvantages of conventional surgical
repair include the extensive recovery period associated with such
surgery; difficulties in suturing the graft to the aorta; the loss
of the existing thrombosis to support and reinforce the graft; the
unsuitability of the surgery for many patients, particularly older
patients exhibiting co-morbid conditions; and the problems
associated with performing the surgical procedure on an emergency
basis after the aneurysm has already ruptured.
In view of the foregoing disadvantages of conventional surgical
repair techniques, techniques have been developed for repairing
abdominal aortic aneurysms by intraluminally delivering an aortic
graft to the aneurysm site through the use of a catheter based
delivery system, and securing the graft within the aorta using an
expandable stent. Since the first documented clinical application
of this technique was reported by Parodi et al. in the Annals of
Vascular Surgery, volume 5, pages 491-499 (1991), the technique has
gained more widespread recognition and is being used more commonly.
As vascular surgeons have become more experienced with this
endovascular technique, however, certain problems have been
encountered. One problem has been the difficult nature of the
procedure. Particularly complex is the step of transferring one leg
of the graft from one iliac artery to the other, which requires the
careful manipulation of numerous catheters and guide wires. Another
problem has been the kinking and/or twisting of the graft both
during and after the graft has been implanted. Still other problems
relate to the need for accurate preoperative measurements to be
made on the morphology of the aneurysm and the surrounding arterial
structure, including the length of the aneurysm, the infrarenal
aortic length and diameter, the length and diameter of the aorta
between the aneurysm and the iliacs, the diameter of the iliacs,
and the angle between the iliacs and the aorta. The difficulty in
making these measurements accurately and the wide variations in
these measurements among patients mandates that the bifurcated
grafts be available in a wide range of sizes and
configurations.
There therefore exists a need for a bifurcated graft and an
implantation method which will overcome the foregoing deficiencies
of the prior art. More particularly, there exists a need for a
modular graft system which will more accurately accommodate the
widely varying arterial sizes in patients, as well as the other
size considerations faced by the surgeon. There also exists a need
for a method for delivering and implanting a bifurcated graft which
avoids the complex procedure for implanting prior art bifurcated
grafts.
SUMMARY OF THE INVENTION
The present invention addresses the needs.
One aspect of the present invention provides a modular prosthesis
for repairing a tubular anatomical structure consisting of a base
member foldable radially between a collapsed configuration and an
expanded configuration and extending longitudinally between a
proximal end and a distal end, a primary tubular limb foldable
radially between a collapsed configuration and an expanded
configuration and having a proximal end and a distal end, and
joining means for intraluminally joining the distal end of the
primary limb to the proximal end of the base member. Preferably,
the joining means includes a friction fit engagement between the
distal end of the primary limb in the expanded configuration and
the proximal end of the base member in the expanded
configuration.
In accordance with one embodiment of the modular prosthesis, the
primary limb may have a first diameter at its proximal end and a
second diameter less that the first diameter at its distal end. In
this regard, the diameter of the primary limb may decrease from the
proximal end toward the distal end at an angle of taper between
about 2 degrees and about 15 degrees. In preferred embodiments, the
primary limb may have a diameter at its proximal end of between
about 16 mm and about 36 mm in the expanded configuration and a
diameter at its distal end of between about 16 mm and about 25 mm
in the expanded configuration. The primary limb may also have a
length from its proximal end to its distal end of between about 6
cm and about 15 cm. Desirably, the primary limb includes an annular
sleeve at its distal end, the annular sleeve having a substantially
uniform diameter. The primary limb may also include securing means
at its proximal end for securing the primary limb to the tubular
anatomical structure.
The base member may have a first diameter at its proximal end and a
second diameter greater than the first diameter at its distal end.
In preferred embodiments, the base member may have a diameter at
its proximal end of between about 16 mm and about 25 mm in the
expanded configuration. The base member may also include an annular
sleeve at its proximal end, the annular sleeve having a
substantially uniform diameter. Preferably, the annular sleeve has
a length between about 2 cm and about 15 cm.
The base member and the primary limb may both consist of a flexible
layer which is radially supported along substantially its entire
length by an expandable stent. In one embodiment, the expandable
stent may be formed from a high shape-memory material. In another
embodiment, the expandable stent may be formed from a low
shape-memory material.
In accordance with another embodiment hereof, the base member may
include dividing means for forming first and second passageways
communicating between the proximal and distal ends of the base
member. The dividing means may include a line of stitching joining
one surface of the base member to an opposite surface of the base
member. Alternatively, the dividing means may include a web of
material arranged longitudinally inside the base member and
defining a first substantially round aperture adjacent the distal
end of the base member and a second substantially round aperture at
a spaced distance from the distal end of the base member. Preferred
embodiments may further include at least one secondary tubular limb
foldable radially between a collapsed configuration and an expanded
configuration and having a proximal end and a distal end, and
connecting means for connecting the proximal end of the secondary
limb to the distal end of the base member.
In accordance with a further embodiment of the present invention, a
modular prosthesis for repairing a tubular anatomical structure
consists of a base member foldable radially between a collapsed
configuration and an expanded configuration and having a proximal
end and a distal end, a primary tubular limb foldable radially
between a collapsed configuration and an expanded configuration and
having a proximal end and a distal end, joining means for
intraluminally joining the distal end of the primary limb to the
proximal end of the base member, at least one secondary tubular
limb foldable radially between a collapsed configuration and an
expanded configuration and having a proximal end and a distal end,
and connecting means for connecting the proximal end of the
secondary limb to the distal end of the base member. The secondary
limb may have a substantially uniform diameter of between about 10
mm and about 25 mm in the expanded configuration. Alternatively,
the proximal end of the secondary limb may have a diameter which is
different than the diameter on its distal end. Preferably, the
secondary limb has a length between its proximal end and its distal
end of between about 4 cm and about 15 cm.
In this last embodiment, the base member may include a main leg on
its proximal end and first and second legs on its distal end. The
main leg may extend in an axial direction and have a main bore
extending longitudinally therein and defining an inlet on its free
end. The first leg may be oriented at a first angle to the axial
direction and have a first bore extending longitudinally therein
and communicating with the main bore, and may define a first outlet
on its free end. The second leg may be oriented at a second angle
to the axial direction and have a second bore extending
longitudinally therein and communicating with the main bore, and
the second leg may define a second outlet on its free end. The
first angle may be different than the second angle, but each of the
first and second angles are preferably between about 10 degrees and
about 60 degrees. Also, the main leg may be oriented in a primary
plane, and at least one of the first and second legs may be
oriented in a plane different than the primary plane.
In a variant of this last embodiment, the base member may include a
crotch defined between the first and second legs, the first leg
having a length between the crotch and the first outlet of between
about 2 cm and about 15 cm. Preferably, the first leg has a
substantially uniform diameter of between about 10 mm and about 25
mm in the expanded configuration, and the second leg has a diameter
which decreases in size from the second outlet toward the main
leg.
This last embodiment may further include another secondary tubular
limb foldable radially between a collapsed configuration and an
expanded configuration and having a proximal end and a distal end,
and attaching means for attaching the proximal end of the another
secondary limb to the distal end of the base member. The another
secondary limb may have a length between its proximal end and its
distal end of between about 4 cm and about 15 cm, and a
substantially uniform diameter of between about 10 mm and about 25
mm in the expanded configuration. Alternatively, the another
secondary limb may have a first diameter at its proximal end and a
second diameter at its distal end different than the first
diameter.
In yet another embodiment of the present invention, a modular
prosthesis for repairing a tubular anatomical structure may consist
of a base member extending longitudinally between a proximal end
defining an inlet and a distal end defining first and second
outlets, the base member being foldable radially between a
collapsed configuration and an expanded configuration, and a
primary tubular limb having a proximal end and a distal end and
being foldable radially between a collapsed configuration and an
expanded configuration. The distal end of the primary limb in the
expanded configuration may be matable in overlapping
circumferential engagement with the inlet of the base member when
the base member is in the expanded configuration to join the
primary limb to the base member. The modular prosthesis may also
include at least one secondary tubular limb having a proximal end
and a distal end and being foldable radially between a collapsed
configuration and an expanded configuration. The proximal end of
the at least one secondary limb may be matable in overlapping
circumferential engagement with one of the first and second outlets
of the base member when the base member is in the expanded
configuration to join the at least one secondary limb to the base
member. Another secondary tubular limb may also be provided in
which its proximal end is matable in overlapping circumferential
engagement with another of the first and second outlets of the base
member when the base member is in the expanded configuration to
join the another secondary limb to the base member.
Another aspect of the present invention provides a prosthesis for
repairing a tubular anatomical structure consisting of a hollow
tubular body constructed from a woven fabric and having a length
defined between a first end and a second end, the first end having
a first diameter and the second end having a second diameter, the
body having a diameter intermediate the first and second ends which
is less than at least one of the first and second diameters. The
first diameter may also be less than the second diameter. The first
end of the body may have a diameter between about 16 mm and about
25 mm and the second end of the body may have a diameter between
about 16 mm and about 36 mm. The diameter of at least a portion of
the body may increase in size at an angle of taper between about 2
degrees and about 15 degrees, preferably at an angle of taper of
about 4 degrees. The body may also have a length between about 6 cm
and about 15 cm. Preferably, the body also includes an annular
sleeve integrally formed at one end, the annular sleeve having a
substantially uniform diameter.
Preferred embodiments of this aspect of the present invention may
further include an expandable stent assembled to the body and
radially supporting the body along substantially the entirety of
its length. The expandable stent may be assembled in the interior
of the body or on the exterior of the body, and may be formed from
a high shape-memory material or from a low shape-memory
material.
Yet another aspect of the present invention provides a method for
repairing a tubular anatomical structure having a proximal branch
and a pair of distal branches projecting from the proximal branch
at a point of bifurcation. A method in accordance with this aspect
of the present invention may include the steps of providing a first
tubular limb foldable radially between a collapsed configuration
and an expanded configuration and having a proximal end and a
distal end, providing a base member foldable radially between a
collapsed configuration and an expanded configuration and having an
inlet and first and second outlets, and providing a primary tubular
limb foldable radially between a collapsed configuration and an
expanded configuration and having a proximal end and a distal end.
The first limb may be fed in the collapsed configuration through
one distal branch until its proximal end is positioned adjacent the
point of bifurcation and its distal end is positioned within the
one distal branch. The first limb may then be expanded from the
collapsed configuration to the expanded configuration whereupon it
engages and becomes secured within the one distal branch.
The base member may then be fed in the collapsed configuration
through the one distal branch and the first limb until the inlet is
positioned in the proximal branch, the first outlet is positioned
within the proximal end of the first limb, and the second outlet is
at least partially aligned with the other distal branch. The base
member may then be expanded from the collapsed configuration to the
expanded configuration, whereupon the first outlet engages the
proximal end of the first limb in friction fit circumferential
contact to join the first outlet of the base member to the first
limb.
The primary limb may be fed in the collapsed configuration through
one of the distal branches and one of the first and second outlets
of the base member until its proximal end is positioned in the
proximal branch and its distal end is positioned within the inlet
of the base member. The primary limb may then be expanded from the
collapsed configuration to the expanded configuration, whereupon
its distal end engages the inlet in friction fit circumferential
contact to join the primary limb to the inlet of the base member
and its proximal end engages and becomes secured within the
proximal branch.
Preferred methods may further include the steps of providing a
second tubular limb foldable radially between a collapsed
configuration and an expanded configuration and having a proximal
end and a distal end, feeding the second limb in the collapsed
configuration through the other distal branch until its proximal
end is positioned within the second outlet of the base member and
its distal end is positioned within the other distal branch, and
expanding the second limb from the collapsed configuration to the
expanded configuration, whereupon its proximal end engages the
second outlet of the base member in friction fit circumferential
contact to join the second limb to the second outlet of the base
member and its distal end engages and becomes secured within the
other distal branch. The steps of feeding and expanding the second
limb may occur prior to the steps of feeding and expanding the
primary limb.
Another method in accordance with the present invention may include
the steps of providing a base member foldable radially between a
collapsed configuration and an expanded configuration and having an
inlet and first and second outlets, and providing a primary tubular
limb foldable radially between a collapsed configuration and an
expanded configuration and having a proximal end and a distal end.
The base member may be fed in the collapsed configuration through
one of the distal branches until the inlet is positioned in the
proximal branch, the first outlet is positioned within the one
distal branch, and the second outlet is at least partially aligned
with the other distal branch, and expanded from the collapsed
configuration to the expanded configuration, whereupon the first
outlet engages and becomes secured within the one distal branch.
The primary limb may be fed in the collapsed configuration through
one of the distal branches and one of the first and second outlets
of the base member until its proximal end is positioned in the
proximal branch and its distal end is positioned within the inlet
of the base member. The primary limb may be expanded from the
collapsed configuration to the expanded configuration, whereupon
its distal end engages the inlet in friction fit circumferential
contact to join the primary limb to the base member and its
proximal end engages and becomes secured within the proximal
branch.
This last method may further include the steps of providing a first
tubular limb foldable radially between a collapsed configuration
and an expanded configuration and having a proximal end and a
distal end, feeding the first limb in the collapsed configuration
through the other distal branch until its proximal end is
positioned within the second outlet of the base member and its
distal end is positioned within the other distal branch, and
expanding the first limb from the collapsed configuration to the
expanded configuration, whereupon its proximal end engages the
second outlet of the base member in friction fit circumferential
contact to join the first limb to the second outlet of the base
member and its distal end engages and becomes secured within the
other distal branch.
A still further method for repairing anatomical structures in
accordance with the present invention may include the steps of
providing a primary tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end, and providing a base member foldable
radially between a collapsed configuration and an expanded
configuration and having a proximal end and a distal end. The
primary limb may be fed in the collapsed configuration through one
distal branch until it is positioned entirely in the proximal
branch, and expanded from the collapsed configuration to the
expanded configuration, whereupon it engages and becomes secured
within the proximal branch. The base member may be fed in the
collapsed configuration through one distal branch until its
proximal end is positioned within the distal end of the primary
limb, and expanded from the collapsed configuration to the expanded
configuration, whereupon its proximal end engages the distal end of
the primary limb in friction fit circumferential contact to join
the base member to the primary limb. In preferred methods, the step
of feeding the base member may include the step of positioning the
base member so that its distal end rests upon the point of
bifurcation when the base member is joined to the primary limb.
In a variant of this last method, the base member may include first
and second passageways providing communication between its proximal
and distal ends, and the method may include the further steps of
providing a first tubular limb foldable radially between a
collapsed configuration and an expanded configuration and having a
proximal end and a distal end, feeding the first limb in the
collapsed configuration through one distal branch until its
proximal end is positioned within one passageway of the base member
and its distal end is positioned within the one distal branch, and
expanding the first limb from the collapsed configuration to the
expanded configuration, whereupon its proximal end engages the one
passageway of the base member in friction fit circumferential
contact to join the first limb to the base member and its distal
end engages and becomes secured within the one distal branch. The
method may further include the steps of providing a second tubular
limb foldable radially between a collapsed configuration and an
expanded configuration and having a proximal end and a distal end,
feeding the second limb in the collapsed configuration through the
other distal branch until its proximal end is positioned within the
other passageway of the base member and its distal end is
positioned within the other distal branch, and expanding the second
limb from the collapsed configuration to the expanded
configuration, whereupon its proximal end engages the other
passageway of the base member in friction fit circumferential
contact to join the second limb to the base member and its distal
end engages and becomes secured within the other distal branch.
Yet a further method for repairing a tubular anatomical structure
in accordance with the present invention may include the steps of
providing a component foldable radially between a collapsed
configuration and an expanded configuration and having a proximal
end with a first diameter, a distal end with a second diameter, a
diameter intermediate its proximal and distal ends which is less
than at least one of the first and second diameters. The component
may be fed in the collapsed configuration through one distal branch
until it is positioned entirely in the proximal branch, and
expanded from the collapsed configuration to the expanded
configuration, whereupon the component engages and becomes secured
within the proximal branch.
In this last method, the component may include first and second
passageways providing communication between its proximal and distal
ends, and the method may include the added steps of providing a
first tubular limb foldable between a collapsed configuration and
an expanded configuration and having a proximal end and a distal
end, feeding the first limb in the collapsed configuration through
one distal branch until its proximal end is positioned within one
passageway of the component and its distal end is positioned within
the one distal branch, and expanding the first limb from the
collapsed configuration to the expanded configuration, whereupon
its proximal end engages within the one passageway of the component
in friction fit circumferential contact to join the first limb to
the component and its distal end engages and becomes secured within
the one distal branch. Preferred methods may further include the
steps of providing a second tubular limb foldable radially between
a collapsed configuration and an expanded configuration and having
a proximal end and a distal end, feeding the second limb in the
collapsed configuration through the other distal branch until its
proximal end is positioned within the other passageway of the
component and its distal end is positioned within the other distal
branch, and expanding the second limb from the collapsed
configuration to the expanded configuration, whereupon its proximal
end engages within the other passageway of the component in
friction fit circumferential contact to join the second limb to the
component and its distal end engages and becomes secured within the
other distal branch.
The modular graft system and surgical methods of the present
invention overcome many of the difficulties associated with
delivering and securing the bifurcated grafts of the prior art. By
providing a graft in the form of modular components that can be
individually selected and assembled together, the present invention
permits more accurate sizing of the graft to the individual
patient. Moreover, the modular system forms grafts having a fully
supported structure which is much stronger than the prior art
grafts and which obviates the prior art procedures in which the
graft is secured by hanging at the proximal neck of the aneurysm,
which arrangement is prone to acute and chronic failure whereby the
graft could become displaced or collapsed. The modular system of
the present invention further takes advantage of the flow of blood
through the individual components to lock the components to one
another, thereby assuring a secure assembly and minimizing the
possibility of leakage.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the subject matter of the present
invention and the various advantages thereof can be realized by
reference to the following detailed description, in which reference
is made to the accompanying drawings in which:
FIG. 1 is a perspective assembled view of a modular system for
forming a bifurcated graft in accordance with one embodiment of the
present invention;
FIG. 2 is an exploded, perspective view of the modular system of
FIG. 1, partially broken away to reveal the stent structures in the
interior thereof;
FIGS. 3A-J are highly schematic partial cross-sectional views of an
abdominal aortic aneurysm showing the sequence of steps to repair
same using the modular system shown in FIG. 1;
FIG. 4 is a perspective assembled view of a modular system in
accordance with an alternate embodiment of the present
invention;
FIGS. 5, 6 and 7 are perspective views of base members for use in
connection with modular systems in accordance with still further
embodiments of the present invention;
FIG. 8 is a perspective view of a component of a modular system in
accordance with yet another embodiment of the present
invention;
FIG. 9 is a perspective view of a delivery catheter assembly for
use in connection with the modular system shown in FIG. 1, the
sheath of the delivery catheter assembly being in the fully
retracted position and being partially broken away to show the
interior thereof; and
FIG. 10 is a cross-sectional view of the delivery catheter assembly
shown in FIG. 9, the sheath thereof being in the fully extended
position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the detailed description which follows, the features of the
present invention will be described in connection with the repair
of an abdominal aortic aneurysm. A typical abdominal aortic
aneurysm is illustrated in FIGS. 3A-J, in which the wall of the
aorta 200 is weakened and forms a bulge 202 in the region between
the renal arteries 204 and the point at which the aorta 200
branches into the right iliac artery 206 and left iliac artery 208.
It will be appreciated, however, that the various features of the
present invention may be readily utilized to repair defects in any
body lumen which branches into two or more lumens. Indeed, the
features of the present invention may be utilized to repair a
variety of defects in a body lumen even where the lumen does not
have branches associated with it.
Referring to FIGS. 1 and 2, there is illustrated one preferred
embodiment of a modular system 100 for forming a bifurcated graft
in accordance with one aspect of the present invention. As used
herein, the term "modular" refers to the fact that system 100
includes a number of individual components which may be separately
delivered by intraluminal techniques to the aneurysm site and then
interconnected with one another in situ to form the bifurcated
graft. Each of the components of modular system 100 is a fully
supported structure which provides sufficient strength to permit
the in situ construction of the bifurcated graft. In accordance
with one embodiment hereof, modular system 100 includes a primary
graft 110, a base member 112, and first and second grafts 114 and
116, respectively, all of which are fabricated as separate
components which may be assembled in preselected size combinations
depending upon the arterial morphology presented by the patient.
Accordingly, each of the various components is preferably provided
in a range of sizes sufficient to accommodate the arterial
morphology which the surgeon is likely to face in the vast majority
of patients.
Primary graft 110 preferably includes a main tapered portion 111
and an annular sleeve 113 having a substantially uniform diameter,
tapered portion 111 and sleeve 113 together defining the overall
length of primary graft 110 between proximal end 110a and distal
end 110b. As used herein, the term "proximal" refers to the end of
a component which is upstream or closest to the heart, and the term
"distal" refers to the end of a component which is downstream or
farthest away from the heart. Primary graft 110 may be provided in
a number of lengths ranging from about 6 cm to about 15 cm in
increments of about 10 mm, and in a number of diameters in the
expanded condition ranging from about 16 mm to about 36 mm at the
proximal end 110a and from about 16 mm to about 25 mm at the distal
end 110b, both in increments of about 2 mm. Preferably, graft 110
is provided in a range of lengths from about 8 cm to about 12 cm at
about 10 mm increments, in a range of diameters at proximal end
110a from about 24 mm to about 36 mm in increments of about 2 mm in
the expanded condition, and with a diameter of about 22 mm in the
expanded condition at distal end 110b. Furthermore, graft 110 may
take the form of a series of two or more grafts which are shorter
in length than graft 110 but which can be assembled to one another
in succession during the surgical procedure described below to form
a primary graft having the desired length.
The tapered portion 111 of primary graft 110 preferably has an
angle of taper between about 2 degrees and about 15 degrees from
the centerline thereof, with an angle of taper of about 4 degrees
being most preferred. It will be appreciated, of course, that the
lengths and diameters of primary graft 110 may be provided in wider
or more narrow increments depending upon the size variations in the
aorta which surgeons experience from patient to patient.
Furthermore, the foregoing dimensions are for use in repairing an
abdominal aneurysm; the components of a modular system for
repairing other body lumens thus may be provided in different size
ranges and in different increments.
Primary graft 110 desirably includes a first series of radiomarkers
118 positioned around the periphery of proximal end 110a, and a
second series of radiomarkers 120 positioned around the periphery
of distal end 110b. Such radiomarkers are conventional in the art
and, when viewed under fluoroscopy, enable the surgeon to identify
and properly locate the ends of primary graft 110 during surgical
implantation. Thus, radiomarkers 118 and 120 may be formed from
biocompatible metals, such as, for example, stainless steel or
platinum-iridium, which are radioopaque, or from radioopaque
polymers.
Grafts 114 and 116 are similar in construction to primary graft
110. Thus, grafts 114 and 116 preferably have a generally
cylindrical tubular construction with graft 114 having a proximal
end 114a and a distal end 114b, and graft 116 having a proximal end
116a and a distal end 116b. Grafts 114 and 116 may be provided in a
number of lengths ranging from about 4 cm to about 15 cm in
increments of about 10 mm, and in a number of diameters in the
expanded condition ranging from about 10 mm to about 25 mm in
increments of about 2 mm. Grafts 114 and 116 preferably are
provided in lengths from about 4 cm to about 8 cm in 10 mm
increments, and with diameters in 2 mm increments from about 12 mm
to about 16 mm in the expanded configuration. In contrast to the
tapered configuration of primary graft 110, grafts 114 and 116 may
have a substantially uniform diameter along their entire lengths
between the proximal and distal ends. However, it is contemplated
that grafts 114 and 116 may have a tapered configuration similar to
that of graft 110, wherein the diameter of the graft may either
increase or decrease from the proximal to the distal end thereof.
Such tapered grafts are particularly useful, for example, in those
situations where the aneurysmal condition extends from the aorta
into the iliac, enabling the graft to have a larger diameter where
it will lie in the bulged portion of the iliac and a smaller
diameter where it will lie in the normal portion of the iliac.
Grafts 114 and 116 also preferably include a series of radiomarkers
at their respective ends. Thus, graft 114 may include a first
series of radiomarkers 122 positioned along the periphery of
proximal end 114a and a second series of radiomarkers 124
positioned along the periphery of distal end 114b. Similarly, graft
116 may include one series of radiomarkers 126 positioned along the
periphery of proximal end 116a and another series of radiomarkers
128 positioned along the periphery of distal end 116b.
Base member 112 is a hollow generally Y-shaped structure formed by
a frustoconical main body 130 which branches into two legs 132 and
134. Leg 132 may have a generally cylindrical shape with a
substantially uniform diameter from its juncture with main body 130
to the free end thereof. Leg 134, on the other hand, defines a
skirt which gradually increases in diameter from its juncture with
main body 130 to its free end. Opposite legs 132 and 134, main body
130 may include an annular sleeve 131 having a substantially
uniform diameter, the free end of which defines an inlet 136 on the
proximal end of base member 112, while outlets 138 and 140 are
defined at the free ends of legs 132 and 134, respectively. Base
member 112 may be formed by the same methods, discussed in detail
below, which are used to form the taper of primary graft 110. That
is, a tapered tubular "blank" may initially be woven with an
annular sleeve 131 formed on one end. Leg 132 may then be created
by sewing upwardly from the enlarged end of the tapered portion and
parallel to the wall thereof with an overlapping edge stitch. The
stitch may then be continued to form the crotch area of base member
112 and then downwardly toward the enlarged end of the tapered
portion and away from the wall thereof to form leg 134.
Subsequently, any excess material between legs 132 and 134 may be
cut away.
As with grafts 110, 114 and 116, base member 112 also may include a
series of radiomarkers for identifying its position during surgical
implantation. Thus, one series of radiomarkers 142 may be
positioned along the periphery of the proximal end of base member
112, another series of radiomarkers 144 may be positioned along the
periphery of the free end of leg 132, and a further series of
radiomarkers 146 may be positioned along the periphery of the free
end of leg 134. Yet another series of radiomarkers 148 may be
arranged around the circumference of leg 134 at its juncture with
main body 130. Finally, base member 112 may include a further
single radiomarker 150 spaced distally from radiomarkers 142 in
alignment with the side of leg 134 opposite leg 132 for indicating
to the surgeon the rotational orientation of base member 112.
Preferably, base member 112 is also provided in a range of sizes
and geometries. In that regard, the various diameters of base
member 112 will most preferably be sized relative to the diameters
of grafts 110, 114 and 116 so that the grafts and base member can
be joined together with a tight, secure fit. Thus, base members 112
may be provided in which annular sleeve 131 has a diameter in the
expanded condition in a range of sizes from about 16 mm to about 25
mm in increments of about 2 mm, with an expanded diameter of about
22 mm being most preferred. Sleeve 131 also may come in a range of
lengths from about 2 cm to about 15 cm in increments of about 10
mm. Similarly, leg 132 may have an expanded diameter in a range of
sizes from about 10 mm to about 25 mm in increments of about 2 mm,
expanded diameters from about 12 mm to about 15 mm being most
preferred, and a length in a range of sizes from about 2 cm to
about 10 cm in increments of about 10 mm. In a preferred
arrangement, leg 134 may be provided with a single diameter at its
juncture with main body 130 of basemember 112, rather than with a
range of different diameters. In such event, graft 116 would be
provided with a corresponding diameter at its proximal end 116a,
and may then taper outwardly to the desired diameter at its distal
end 116b. Alternatively, leg 134 may be provided in a range of
diameters at its juncture with main body 130 to correspond to the
diameter of graft 116 where a graft 116 having a uniform diameter
within a range of diameters is employed.
As noted above, base member 112 may also be provided with different
geometries. That is, the angle at which legs 132 and 134 project
from the longitudinal centerline C of main body 130 may be varied
to accommodate differences in arterial morphology from one patient
to the next. Accordingly, base members 112 may be provided such
that leg 132 projects from centerline C at one of a number of
different angles .alpha. ranging from about 10 degrees to about 60
degrees, in increments of about 5 degrees. Similarly, base members
112 may be provided in which leg 134 projects from centerline C at
one of a number of different angles .beta. ranging from about 10
degrees to about 60 degrees, in increments of about 5 degrees. Legs
132 and 134 need not project at the same angle from longitudinal
centerline C. In other words, the angles at which legs 132 and 134
project from main body 130 may be determined independently of one
another so as to conform as closely as possible to the arterial
geometry of the patient. Moreover, the centerlines of legs 132 and
134 need not lie in the same plane as the centerline C of main body
130, but may project from centerline C in a third dimension
(outwardly from the page) at one of a number of different angles
ranging from about 0 degrees to about 90 degrees, in increments of
about 5 degrees. While legs 132 and 134 would typically project at
the same angle from centerline C in the third dimension, this need
not be the case and base members 112 may be provided in which legs
132 and 134 project at different angles from one another in the
third dimension.
Each of grafts 110, 114 and 116 preferably consists of a flexible
outer layer 152 which is supported internally along substantially
its entire length by an expandable stent 154 which assumes a
generally cylindrical or tapered configuration in the expanded
condition, depending upon the configuration it is given when
initially formed, and which provides the graft with sufficient
structural strength to permit the components of modular system 10
to be assembled to one another in situ. In the case of primary
graft 110, stent 154 may protrude beyond the proximal end 110a
thereof and include one or more barbs 156 for anchoring graft 110
to the wall of aorta 200 to assist in holding modular assembly 100
in place. Alternatively, stent 154 may occupy the exterior of
grafts 110, 114 and 116, with the flexible layer 152 extending
longitudinally therethrough.
Outer layer 152 is preferably formed from a biocompatible material
having sufficient strength to withstand the surgical implantation
procedure described more fully below and to withstand the blood
flow and other biomechanical forces which will be exerted on
modular system 100. Such materials may include, for example,
polyester materials, such as DACRON.RTM., polytetrafluoroethylene,
expanded polytetrafluoroethylene, polyester materials coated with
polytetrafluoroethylene, polyurethane, expanded polyurethane and
silicone. Outer layers 152 formed from woven materials are
preferred. To reduce the bulk and facilitate the intraluminal
delivery of grafts 110, 114 and 116, outer layer 152 preferably has
a thickness of about 0.1 mm which is about one-third the thickness
of conventional graft materials. It will be appreciated, of course,
that the present invention can be practiced using materials which
are greater than 0.1 mm in thickness, including conventional graft
materials.
Methods for forming tubular woven articles having a uniform
diameter are well known in the art and are commonly employed in
fabricating conventional grafts. Such methods may be utilized to
fabricate the outer layer 152 of grafts 114 and 116. Typical
methods make use of a narrow fabric weaving loom where warp threads
(i.e., those threads extending in the longitudinal direction of the
tube) and weft threads (i.e., those threads extending transverse to
the longitudinal direction of the tube) are interlaced with one
another. At the weaving station of the loom, the warp threads are
fed individually through heddles aligned transverse to the
longitudinal direction on one of four or more shafts. The upward
and downward movement of the shafts moves a preselected pattern of
the warp threads up and then down, two of the shafts moving the
warp threads for forming the upper surface of the tube, and two of
the shafts moving the warp threads for forming the lower surface of
the tube. As the warp threads on one shaft are drawn upwardly and
the warp threads on another shaft are drawn downwardly, the weft
thread is shuttled in a first direction between those groups of
warp threads to weave the upper surface of the tube. The weft
thread is then shuttled in a reverse direction between another
group of upwardly and downwardly drawn warp threads to weave the
lower surface of the tube. The position of the shafts and thus the
position of the warp threads is then reversed and the weft thread
is again shuttled between the groups of warp threads, the process
continuing to weave a tubular shape.
As they approach the weaving station, the warp threads are fed
between the fingers of a front reed which align the threads for
weaving and which thus determine the ultimate shape of the woven
article. For weaving tubular articles having a substantially
constant diameter, such as outer layer 152 of grafts 114 and 116, a
conventional front reed which is fixed in place and which has
evenly spaced fingers is used to produce constant spacing between
the warp threads. Where a tubular article having a gradually
increasing or decreasing diameter is desired, however, the
conventional reed is replaced with a fan-shaped reed in which the
spacing between the fingers is narrow at the bottom and gradually
increases toward the top. Such fan-shaped reeds are conventional in
the textile industry, and find use for such applications as weaving
tapered flat camera straps. In such processes, the reeds are not
held in a fixed position, but rather are moved upward or downward
to alter the diameter of the article being woven. Thus, when the
fan-shaped reed is gradually moved downward as the weaving of the
tube advances, the spacing between the warp threads and, hence, the
diameter of the tubular article being woven will gradually be
increased. Similarly, when the reed is gradually moved upward as
the weaving of the tube advances, the spacing between the warp
threads will decrease as will the diameter of the tubular article
being woven. The rate of movement of the reed will determine the
taper of the article being woven; the faster the reed is moved, the
larger the angle of taper, and the slower the reed is moved, the
smaller the angle of taper. Moving the reed at a constant rate will
produce a constant angle of taper. However, changing the rate of
movement of the reed enables tubular articles to be formed with
curved or changing angles of taper (as shown in FIGS. 7 and 8). The
upward or downward movement of the reed, and therefore the degree
of taper in the woven article, can be controlled in a known fashion
by the use of a stepping motor and a system controller.
As the space between the warp threads is increased to weave a
tubular article with an increasing diameter, it is desirable to
decrease the spacing between the weft threads so as to maintain the
structural integrity of the article being woven. This also can be
accomplished in a conventional fashion by employing a
solenoid-activated mechanism to withdraw the working pawl in the
conventional pawl and ratchet fabric take off system from its
normal operating position. Operation of the solenoid can also be
dictated by the system controller.
Weaving processes employing a movable fan-shaped reed can be
employed to form the outer layer 152 for tapered graft 110. In such
process, the front fan-shaped reed of the loom would initially be
held in a fixed upper position to weave the substantially uniform
diameter tube for annular sleeve 113. When the annular sleeve 113
reaches the desired length, the front reed would be drawn downward
at a rate which would produce the desired angle of taper. The front
reed would continue to be drawn downward as the weaving process
continues until a layer 152 having the desired tubular
configuration has been formed.
Stent 154 may be formed from a wire or the like of a low
shape-memory material which has been bent back and forth in a
curved pattern in the longitudinal direction of the graft and then
wrapped in a circumferential direction transverse to the
longitudinal direction to form one or more loops of a predetermined
circumference. As used herein, the term "low shape-memory material"
refers to a material that, once deformed from an initial shape to a
subsequent shape, will tend to maintain the subsequent shape and
not return to the initial shape. Such materials preferably include
biocompatible metals, including, for example, stainless steel,
titanium, tantalum, gold, platinum, copper and the like, as well as
alloys of these metals. Biocompatible low shape-memory plastics may
also be used to form stent 154. Alternatively, stent 154 may be
formed from a high shape-memory plastic or alloy, such as nitinol,
which automatically transforms from one shape to another shape as
its temperature passes through a critical point. Whether stent 154
is formed from a low shape-memory material or from a high
shape-memory material is not critical, and impacts on the present
invention predominantly in terms of the technique used to
intraluminally deliver the components of modular system 100 to the
aneurysm site and fix same in place. The structure of preferred
stents 154 and methods for forming same are disclosed in commonly
assigned U.S. patent application Ser. No. 08/353,066 entitled "High
Hoop Strength Intraluminal Stent", the disclosure of which is
incorporated by reference herein.
Base member 112 is similar in construction to grafts 110, 114 and
116, and includes a flexible outer layer 160 which is ordinarily
formed from the same materials as outer layer 152. An expandable
generally Y-shaped stent 162 internally supports outer layer 160
along substantially its entire length, providing structural
strength thereto, and is ordinarily formed from the same materials
and by the same methods as stent 154. As with grafts 110, 114 and
116, base member 112 may be constructed with stent 162 on the
exterior and flexible layer 160 arranged interior thereof.
Grafts 110, 114 and 116 and base member 112 are each radially
expandable from a collapsed condition in which the circumferences
thereof are minimized so that the components can be delivered to
the site of the aortic aneurysm intraluminally, to an expanded
condition in which the circumference of each of the components
approaches a predetermined maximum circumference. As will be
described more fully below, each component is normally held in the
collapsed condition by the outer sheath of a catheter during
intraluminal delivery. Once properly located, the component is
deployed from the catheter and radially expanded until its
circumference firmly contacts the interior wall of either the
artery in which it is situated or the component to which it is
being connected to hold the graft in this implanted location.
Once the proper sizes for the various components of modular system
100 have been selected, the components are preferably preloaded
into one or more disposable delivery catheter assemblies which then
may be used by the surgeon to intraluminally introduce the
components into the patient and to assemble same to one another in
the form of a bifurcated graft. One such delivery catheter assembly
300 is shown in FIGS. 9-10. Delivery catheter assembly 300 includes
an elongated tubular outer sheath 302 formed from a conventional
polymer which is sufficiently flexible that it will readily bend as
catheter assembly 300 is fed through the arterial path during the
intraluminal surgical procedure. Typical materials for forming
sheath 302 include, for example, nylon, teflon
polytetrafluoroethylene, polyethylene and the like. The forward end
302a of sheath 302 may include a radiomarker 304 for readily
identifying and locating end 302a under fluoroscopy. Radiomarker
304 may take the form of an annular ring formed from a metal, such
as stainless steel or platinum-iridium, or a radioopaque polymer,
or may consist of any radioopaque material applied to the end 302a
of sheath 302. At its rearward end 302b, sheath 302 may include a
conventional T-handle 306 having finger grips 308 and a hollow stem
310.
An inner tubular member 312 is arranged in sheath 302 for slidable
longitudinal movement with respect thereto. Tubular member 312
defines a continuous internal passageway 313 through delivery
catheter 300 so that the delivery catheter can be assembled onto
and follow a guidewire during the intraluminal delivery procedure.
In that regard, tubular member 312 may be formed from any
biocompatible material which resists kinking. In a preferred
arrangement, however, tubular member 312 includes a coiled,
spring-like wire 314 which is flexible, yet which has sufficient
radial strength to resist collapsing due to the forces exerted by
the components of modular system 100 when they are loaded in
delivery catheter 300. In a highly preferred arrangement, the coil
314 may be surrounded by a thin-walled polymer tube 316 or coated
with an impervious polymer layer (not shown) so that medications,
dyes and the like may be supplied through passageway 313 to the
abdominal aorta repair site.
At one end of coil 314, tubular member 312 includes a tip 318 which
may be formed from a biocompatible polymer, such as polyurethane,
teflon polytetrafluoroethylene, nylon or the like, with a
conventional radioopaque marker (not shown) formed or assembled
thereon. Tip 318 preferably has an outer diameter which is larger
than the inner diameter of sheath 302 so that tip 318 cannot be
drawn into sheath 302 as the sheath and tubular member 312 are
moved relative to one another. The forward end of tip 318
preferably has a smoothly curved surface 320 to facilitate the
forward movement of delivery catheter assembly 300 through the
arterial system. At its rearward end, tip 318 may include a reduced
diameter portion 322 sized to fit within the sheath 302 so as to
axially align tip 318 with sheath 302 in the mated condition and
seal the end 302a of the sheath. A bore 324 in tip 318 communicates
with the passageway 313 in tubular member 312 to enable a
guidewire, medication, dye and the like to exit from delivery
catheter assembly 300.
At the opposite end of coil 314, tubular member 312 may include a
stabilizer tube 326 which extends outwardly of sheath 302 through
the hollow stem 310 of T-handle 306. Stabilizer tube 326 may be
formed from any biocompatible material, including polymers such as
polyurethane, teflon polytetrafluoroethylene and nylon, and metals,
such as stainless steel. A thumbscrew 328 in T-handle 306 may be
actuated to engage stabilizer tube 326, thereby locking tubular
member 332 in place with respect to sheath 302. Exterior of sheath
302, stabilizer tube 326 may be fitted with a conventional hand
grip 330 and any number of conventional accessories, such as the
Y-connector 332, hemostasis valve 334 and stopcock 336 illustrated
in FIG. 9.
A cylindrical spacer 331 formed on tubular member 312 at a spaced
distance from the rearward end of tip 318 defines a first annular
cavity 333 within sheath 302 for holding and delivering the first
component of modular system 100 to be deployed during the surgical
procedure described below, in this case graft 114. Spacer 331 may
also be formed from any biocompatible material, including
polyurethane, teflon polytetrafluoroethylene, nylon and stainless
steel, and preferably includes a radiomarker (not shown) so that
its position can be identified by fluoroscopy during the surgical
procedure. The length of cavity 333 will depend upon the length of
the particular component of modular system 100 to be assembled
therein. Thus, cavity 333 preferably will be sufficiently long to
accommodate the component, but not so long that there is a
substantial unsupported gap between the end of the component and
either tip 318 or spacer 331 which may permit sheath 302 to kink as
a result of the axial forces applied to feed delivery catheter
assembly 300 through the arterial system.
A second spacer 335 having generally the same construction as
spacer 331 is formed on tubular member 312 at a spaced distance
from the first spacer 331, thus defining a second annular cavity
337 within sheath 302 for holding and delivering the second
component of modular system 100 to be deployed during the surgical
procedure, in this case base member 112. The length of cavity 337
will be sufficient to accommodate base member 112, but not so long
that there is a significant unsupported gap between base member 112
and either spacer 331 or spacer 335.
Delivery catheter assembly 300 further includes a coiled,
spring-like wire 340 assembled in sheath 302 between spacer 335 and
the end of stabilizer tube 326. Coil 340 radially supports sheath
302 to prevent the kinking of same and provides a structure for
transferring the axial load applied through T-handle 306 to spacers
335 and 331, while at the same time not detracting from the overall
flexibility of delivery catheter assembly 300.
A method for introducing and assembling the various components of
modular system 100 to repair an abdominal aortic aneurysm will now
be described with reference to FIGS. 3A-J. The described method
assumes that the stents 154 within grafts 110, 114 and 116 and the
stent 162 within base member 112 are formed from a memory metal,
such that the stents, and hence each of the components, will
radially expand automatically as their temperature reaches the
transition temperature for the memory metal following deployment
within the body. From the method described hereinafter, methods
employing balloon expansion techniques for introducing and
assembling the components of a modular system 100 in which stents
154 and 162 are formed from low shape-memory materials will be
readily apparent to one skilled in the art. Accordingly, a detailed
description of such methods is not provided herein.
Thus, in a repair method of the present invention, an arteriotomy
is initially performed on the right leg and, under conventional
fluoroscopic guidance techniques, a first guidewire 400 is
introduced through the right femoral artery (not shown) and right
iliac 206 into the aorta 200. Delivery catheter assembly 300
containing in succession graft 114 and base member 112 may then be
assembled on guidewire 400, the guidewire being threaded through
passageway 313 in tubular member 312 and advanced under
fluoroscopic guidance until the end 302a of sheath 302 is
positioned adjacent the junction of right iliac 206 and aorta 200,
as shown in FIG. 3A. At this point, thumbscrew 328 may be loosened
and T-handle 306 of delivery catheter assembly 300 pulled backward
to partially retract sheath 302 with respect to tubular member 312,
thereby exposing the proximal end 114a of graft 114 as illustrated
in FIG. 3B. Sheath 302 may then be retracted further to the
position illustrated in FIG. 3C wherein the end 302a thereof is
aligned with spacer 331, at which point the first annular cavity
333 will be completely open and the entirety of graft 114 will be
exposed. With sheath 302 no longer insulating graft 114 and
retaining it in the collapsed condition, graft 114 will expand
radially as its temperature increases through the transition
temperature of the memory metal forming the stent 154 therein. This
radial expansion will continue until the outer layer 152 of graft
114 firmly engages the interior wall of iliac 206 to hold graft 114
in this implanted location.
Following deployment of graft 114, thumbscrew 328 may be tightened
to lock sheath 302 relative to tubular member 312 and delivery
catheter assembly 300 may be advanced as a unit into the base of
aneurysm 202, as shown in FIG. 3D, until the radiomarkers 144 on
leg 132 of base member 112 are aligned within the proximal end l14a
of graft 114, at a spaced distance below the radiomarkers 122. This
distance should be such as to provide a sufficient overlap between
the proximal end 114a of graft 114 and the free end of leg 132 that
a secure connection will be formed between these members. Once
properly positioned, thumbscrew 328 may be loosened and the outer
sheath 302 of delivery catheter assembly 300 retracted relative to
tubular member 312 to expose sleeve 131 on the proximal end of base
member 112. At this point, the surgeon may look for the single
radiomarker 150 just inwardly of radiomarkers 142 to assure that
leg 134 of base member 112 is in alignment with left iliac 208. If
leg 134 is not properly aligned, delivery catheter assembly 300 may
be rotated until such alignment is achieved. With base member 112
properly positioned, sheath 302 may be retracted further as shown
in FIG. 3E until the end 302a thereof is aligned with spacer 335,
whereupon the second annular cavity 337 will be completely open and
the entirety of base member 112 will be exposed. Again, without
sheath 302 retaining it in the collapsed condition, base member 112
will expand radially until the free end of leg 132 contacts and
firmly engages the interior wall on the proximal end 114a of graft
114 in overlapping relationship. Forming leg 132 of base member 112
with a diameter in the fully expanded condition which is larger
than the fully expanded diameter of graft 114 will assure that the
foregoing assembly procedure securely locks base member 112 and
graft 114 together and forms a seal which prevents the leakage of
blood from therebetween.
With graft 114 and base member 112 deployed and assembled together,
tubular member 312 may be retracted with respect to sheath 302
until the reduced portion 322 of tip 318 is positioned within the
end 302a of sheath 302. Thumbscrew 328 may then be tightened to
lock these two elements together and the entire delivery catheter
assembly 300 may be withdrawn from the patient, with guidewire 400
being retracted into right iliac 206 and temporarily left in place
therein. A second arteriotomy may then be performed on the left leg
of the patient and, again under fluoroscopic guidance, a second
guidewire 410 may be introduced up through the left femoral artery
(not shown), through the left iliac 208, into base member 112
through the outlet 140 defined at the free end of leg 134, and
finally out through the inlet 136 defined at the free end of sleeve
131. With guidewire 410 in place, guidewire 400 may be fully
withdrawn from the patient. A second delivery catheter assembly 500
containing in succession grafts 116 and 110 may then be advanced
over guidewire 410 through the left femoral artery and left iliac
208 until the tip 518 thereof is positioned within leg 134 of base
member 112, with radiomarkers 126 on the proximal end 116a of graft
116 located a spaced distance above radiomarkers 148 on base member
112 at the juncture of leg 134 and main body 130, all as
illustrated in FIG. 3F. When delivery catheter assembly 500 has
been properly positioned, the thumbscrew thereon (not shown) may be
loosened and sheath 502 partially retracted with respect to tubular
member 512, thereby exposing the proximal end 116a of graft 116.
With sheath 502 no longer holding the proximal end 116a of graft
116 in the collapsed condition, the proximal end will begin to
expand radially until it contacts and firmly engages the inner wall
of base member 112 at the juncture between main body 130 and leg
134. Again, a secure leakproof assembly of graft 116 to base member
112 can be obtained by assuring that the diameter of graft 116 in
the fully expanded condition is greater than the diameter of base
member 112 at the juncture between main body 130 and leg 134, and
that a sufficient portion of the proximal end 116a of graft 116 is
located above this juncture. The remainder of graft 116 may then be
deployed as shown in FIG. 3H by retracting sheath 502 further until
the end 502a thereof is aligned with spacer 530.
Once graft 116 has been deployed, guidewire 410 may be advanced
until the end thereof is positioned above the renal arteries 204.
The thumbscrew on delivery catheter assembly 500 may be tightened
to lock sheath 502 relative to tubular member 512 and the delivery
catheter assembly may then be advanced over guidewire 410 to the
position shown in FIG. 3H, wherein the radiomarkers 120 on the
distal end 110b of graft 110 are positioned within sleeve 131 of
base member 112, but at a spaced distance below radiomarkers 142.
When primary graft 110 has been properly located with respect to
base member 112, i.e., with a sufficient overlap between the distal
end 110b of graft 110 and the proximal end of base member 112, the
thumbscrew on delivery catheter assembly 500 may be loosened and
sheath 502 retracted relative to tubular member 512 to expose the
proximal end 110a of graft 110. As illustrated in FIG. 3I, with
sheath 502 no longer holding it in the collapsed condition, the
proximal end 110a of graft 110 will expand radially until the outer
layer thereof firmly engages the interior wall of aorta 200. This
radial expansion will also cause the barbs 156 on the proximal end
of graft 110 to contact the inner wall of aorta 200. Tightening the
thumbscrew thereof and then tugging slightly on delivery catheter
assembly 500 will assure that barbs 156 grab into the inner wall of
aorta 200 to assist in holding primary graft 110 and, hence, the
proximal end of modular system 100 in place. With barbs 156
securely engaged, the thumbscrew may be loosened and sheath 502
retracted relative to tubular member 512 until the tip 502a of the
sheath is aligned with spacer 534 to expose and deploy the
remainder of primary graft 110. As primary graft 110 is fully
deployed, the distal end 110b thereof will expand radially until it
firmly engages the interior wall of sleeve 131, securely locking
primary graft 110 to base member 112 in a leakproof arrangement.
Tubular member 512 may then be retracted relative to sheath 502
until the reduced diameter portion 522 of its tip 518 is positioned
within the end 502a of the sheath. Tubular member 512 may then be
locked to sheath 502 by tightening the thumbscrew of delivery
catheter assembly 500, and the entire assembly may be withdrawn
from the patient. Subsequently, guidewire 410 may be withdrawn from
the patient and the arteriotomies sutured.
Once deployed and assembled together according to the foregoing
procedure, the components of modular system 100 form a bifurcated
graft which is fully self supporting. That is, as a result of its
bottom-up assembly, the biomechanical forces exerted on the graft,
particularly from the flow of blood, are supported along its entire
length in a columnar fashion.
It will be appreciated, of course, that variations in the foregoing
procedure can be made without departing from the scope of the
present invention. For example, delivery catheter assembly 300 may
be fabricated with three spacers defining three annular cavities in
succession, with graft 114 loaded in the first annular cavity, base
member 112 loaded in the second annular cavity and primary graft
110 loaded in the third annular cavity. In such event, graft 114
and base member 112 may be deployed in succession as described
above, following which the delivery catheter assembly may be
advanced to deploy primary graft 110. Subsequently, graft 116 would
be deployed and assembled to base member 112 as described above
utilizing a second delivery catheter assembly having only one
spacer defining a single annular cavity for holding graft 116.
Other variations from the foregoing method are also possible. In
this regard, rather than relying merely upon the outward radial
forces exerted by the expanding stent structures of grafts 110 and
116 and base member 112 to securely lock the components together,
the appropriate ends of these components may be provided with
mechanical structures, such as barbs, sutures and the like, to
assure that the components are securely held together.
By changing the configuration of the various components of the
modular system, still other variations in the surgical procedure
are possible. Thus, referring to FIG. 4, the modular system may
include a base member 550 having an integral elongated leg 552. Leg
552 would typically be formed with a substantially uniform diameter
and a sufficient length that at least the distal end 554 thereof
will securely engage right iliac 206 upon the deployment of base
member 550, thereby eliminating the need to deploy a separate graft
in right iliac 206 and connect the base member thereto, as in the
case with graft 114 and base member 112 described above. As a
result, the use of base member 550 results in a simpler surgical
procedure while maintaining substantially all of the advantages
associated with the modular system 100 of the present
invention.
Furthermore, the base member need not have integrally formed legs
depending distally therefrom. For example, in accordance with
another embodiment of the present invention, the modular system may
include a base member 600 such as shown in FIG. 5. Base member 600
has a generally frustoconical main body 602 which gradually
decreases in diameter from the distal end 600b of the base member
to its juncture with an annular sleeve 604. Sleeve 604 has a
substantially uniform diameter until its terminus at the proximal
end 600a of base member 600. The main body 602 of base member 600
is divided into two portions 606 and 608 by a web 610 which extends
from the distal end 600b of the base member to the juncture between
main body 602 and sleeve 604. Web 610 is connected within base
member 600, such as by sewing, heat welding or the like, so as to
define a substantially circular opening 612 on one side of the
distal end 600b of base member 600, and another substantially
circular opening 614 on the other side of base member 600 at the
juncture between main body 602 and annular sleeve 604. The diameter
of opening 612 is preferably large enough to readily accept the
proximal end 116a of graft 116, but not so large as to interfere
with the insertion of the proximal end 114a of graft 114 into the
remaining crescent-shaped opening 616 at the distal end 600b of
base member 600. Hence, the diameter of opening 612 is preferably
between about one half and three quarters of the diameter of base
member 600 at its distal end. As for opening 614, it preferably has
a diameter which is smaller than the fully expanded diameter of
graft 114 at its proximal end 114a.
As with the components of modular system 100 described above, base
member 600 preferably consists of a flexible outer layer 618 which
is supported internally along substantially its entire length by an
expandable stent 620. In a preferred arrangement, web 610 is
connected within base member 600 after stent 620 has been placed
within outer layer 618.
Base member 600 may also be provided with a plurality of
radiomarkers for locating the various regions thereof under
fluoroscopy. Thus, base member 600 may include one series of
radiomarkers 619 around the periphery of proximal end 600a, another
series of radiomarkers 621 around the periphery of distal end 600b,
and another series of radiomarkers 622 formed around the periphery
of base member 600 at the juncture between main body 602 and
annular sleeve 604. A further single radiomarker 624 may be
positioned distally of radiomarkers 622 in alignment with the side
of base member 600 opposite opening 614 for indicating the
rotational orientation of the base member.
The procedure for implanting and assembling a modular system
incorporating base member 600 is different from that described
above where the modular system utilizes base member 112. More
particularly, rather than deploying and assembling the components
from the bottom up as described above, when a base member 600 is
utilized the components are deployed and assembled from the top
down. That is, the primary graft 110 would be the first component
deployed followed by base member 600. In this procedure, however,
rather than inserting and expanding the distal end 110b of primary
graft 110 within the proximal end of the base member to join these
components together, just the opposite procedure is performed. In
other words, once primary graft 110 has been deployed, base member
600 would be deployed so that its proximal end 600a is inserted
into and expands within the distal end 110b of primary graft 110.
Subsequently, graft 116 may be fed upwardly until its proximal end
116a enters base member 600 through opening 612. With the proximal
end 116a of graft 116 positioned at a spaced distance above opening
612 (as determined by radiomarkers appropriately placed on the
components), graft 116 may be deployed whereupon it will become
securely locked within portion 608 of base member 600, with the
substantially circular periphery of graft 116 sealing against the
substantially circular periphery of opening 612 to prevent the
leakage of blood therebetween. As it radially expands, the distal
end 116b of graft 116 will engage and become secured within left
iliac 208. Graft 110, base member 600 and graft 116 may be deployed
in succession from a single delivery catheter assembly similar in
construction to delivery catheter assembly 300, yet having a series
of three annular cavities. A second delivery catheter assembly may
be fed through crescent-shaped opening 616 in base member 600 and
then upwardly therefrom to position the proximal end 114a of graft
114 at a spaced distance above opening 614 (also as determined by
appropriately placed radiomarkers). Upon deployment of graft 114 in
this position, the substantially circular periphery thereof will
firmly engage the substantially circular periphery of opening 614
to similarly seal against the leakage of blood from therebetween.
The distal end 114b of graft 114, as it radially expands, will
engage and become secured within right iliac 206.
In a variant of the foregoing embodiment, the base member may be
formed with the general shape of base member 600, but without the
internal web 610. A base member 650 in accordance with this
embodiment is illustrated in FIG. 6. Base member 650 is intended to
be used in those situations in which the modular system is to be
assembled with no iliac grafts 114 and 116. Thus, the modular
system would include primary graft 110 and base member 650 which
may be deployed either as described immediately above in connection
with base member 600 (i.e., primary graft 110 first followed by
base member 650), or as described previously in connection with
base member 112 (i.e., base member 650 first followed by primary
graft 110). However, in positioning base member 650, the surgeon
would ensure not only that the proximal end 650a of base member 650
will overlap with the distal end 110b of graft 110, but also that
the distal end 650b of base member 650 will lie against the apex
between iliacs 206 and 208, whereby the arterial wall at the apex
may support the modular system in its fully deployed and assembled
condition. In this scenario, blood flow into graft 110 and through
base member 650 will divide at the apex as it exits from the distal
end 650b of the base member and will flow into both the right iliac
206 and left iliac 208.
A still further embodiment of a base member 700 in accordance with
the present invention is shown in FIG. 7. In one region 702
extending from proximal end 700a along a major portion of its
length, base member 700 has a substantially uniform diameter. The
diameter of base member 700 then gradually increases in a second
region 704 thereof until its terminus at distal end 700b. Tapered
region 704 may be formed by the same methods used to form the taper
of primary graft 110, as discussed more fully above.
Base member 700 further includes a stitch line 706 which extends in
the longitudinal direction thereof within region 702, the stitch
line joining the outer layer 708 on the diametrically opposed
surfaces of base member 700 to define two tubular channels 710 and
712 intermediate proximal end 700a and distal end 700b. As with the
other components of the modular systems described above, the outer
layer 708 of base member 700 is supported internally along
substantially its entire length by an expandable stent 714. In that
regard, stent 714 may consist of an assembly of several members
which independently support tapered region 704, tubular channels
710 and 712, and the proximal end of base member 700. Base member
700 may also be provided with radiomarkers, including one series of
radiomarkers 716 formed around the periphery of proximal end 700a,
another series of radiomarkers 718 formed around the periphery of
distal end 700b, and another series of radiomarkers 720 formed
around the periphery of the base member at the distal end of stitch
line 706. In addition, base member 700 may include a further single
radiomarker 722 spaced distally of radiomarkers 716 in alignment
with the side of tubular channel 712 opposite tubular channel 710
for indicating the rotational orientation of the base member.
In a variant of this embodiment, tubular channels 710 and 712 may
consist of tubes of substantially uniform diameter which are
independent of one another. Such embodiment would look similar to
base member 700 as illustrated in FIG. 7, but would have an
elongated through hole in place of stitch line 706. Such embodiment
may be formed, for example, from two devices having a tapered
region (as at 704) and two tubular legs extending from the tapered
region, one device being inverted relative to the other and the
devices being joined to one another at their tubular legs.
One procedure for implanting and assembling a modular system
incorporating base member 700 may be similar to that described
above in connection with base member 600. That is, the primary
graft 110 would be deployed first, following which base member 700
may be deployed with its proximal end 700a inserted into and
expanded within the distal end 110b of primary graft 110. Graft 114
may then be fed upwardly until its proximal end 114a resides within
tubular channel 710 at a spaced distance above radiomarkers 720.
Upon its deployment, the proximal end 114a of graft 114 will become
securely locked within tubular channel 710 and the distal end 114b
thereof will engage and become secured within right iliac 206.
Graft 116 may then be fed upwardly until its proximal end 116a lies
within tubular channel 712 at a spaced distance above radiomarkers
720. Upon deployment of graft 116, the proximal end 116a thereof
will become securely locked within tubular channel 712 and the
distal end 116b thereof will engage and become secured within left
iliac 208. It will be appreciated from the foregoing that graft
110, base member 700 and graft 114 may be deployed in succession
from a first delivery catheter assembly, with graft 116 being
deployed from a second delivery catheter assembly. In an alternate
procedure employing base member 700, the base member may be
deployed first, followed in succession by grafts 110, 114 and
116.
In a variant of the foregoing embodiment, base member 700 and graft
110 may be combined as a single component 750, illustrated in FIG.
8. Component 750 thus may include a bottom portion 752 which has
substantially the same structure as base member 700 described
above, including a region 754 having a substantially uniform
diameter, a region 756 which gradually increases in diameter as it
approaches the distal end 750b of component 750, and a stitch line
758 which defines two tubular channels 760 and 762 within component
750. At its upper end, component 750 includes an integrally formed
region 764 which begins with a substantially uniform diameter and
which gradually increases in diameter as it approaches the proximal
end 750a thereof. Forming portions 752 and 764 as a single integral
unit thus eliminates the need to deploy a separate graft 110 within
aorta 200 and connect the base member thereto. As a result, modular
systems incorporating component 750 provide all of the advantages
of the present invention while allowing for a simpler surgical
procedure.
Although the invention herein has been described with reference to
particular embodiments, it is to be understood that these
embodiments are merely illustrative of the principles and
applications of the present invention. It is therefore to be
understood that numerous modifications may be made to the
illustrative embodiments and that other arrangements may be devised
without departing from the spirit and scope of the present
invention as defined by the appended claims.
* * * * *